The invention relates to a resilient compressible element having at least two lamina, one of which is a compressible layer and the other of which is a thermosol. The preferred compressible material is that shown in U.S. Pat. No. 3,147,698, which patent shows the material used in laminates. U.S. Pat. No. 3,652,376 discloses additional laminates utilizing the compressible element of the aforesaid U.S. Pat. No. 3,147,698. Thermosol materials using polyvinyl chloride plastisol together with the crosslinking monomers 1,3-butylene dimethacrylate and trimethylolpropane trimethacrylate are shown in the sales brochure of Rohm and Hass Company, CM-32, a copy of which accompanies the present application with the Notice of References.
It is an object of the present invention to provide an improved printers packing that will outperform all known packings.
It is the further object of the present invention to provide a new composition of matter that will make possible the accomplishment of the aforesaid object.
A still further object of the present invention is to provide a superior method of manufacturing printers packing and similar printers elements. Such a superior method should have as few disadvantages as possible, for example, substantially eliminating pollution, reducing cost, and conserving energy. The present invention in particular increases the productivity of labor, manufacturing equipment and space.
To give just some view of disadvantages inherent in prior procedures known to have been used in producing printing elements, solvent laid elastomers generally require a number of coating passes or a number of in-line coatings to enable the expeditious removal of the solvent. Elastomers applied by milling have the disadvantage of poor adhesion, trapping air and difficult caliper control. While plastisols are not known to have been used to produce resilient compressible printing elements they would have the obvious disadvantage of being subject to heat deformation, poor solvent resistance and poor impact resistance.
It might be thought that thermosols would also have disadvantages such as instability of solution viscosity and likely precuring prior to good lamination, but surprisingly it has been found that the thermosols are not only easily coated on to the desired compressible laminas but the thermosols can be formed into sufficiently resilient lamina with sufficient integrity to give improved resistance to collapse over long usage compared to the laminate structures of the prior art.